The present invention relates to an electrical control method and apparatus for a combustion engine, and more particularly to an improvement in a method and apparatus for controlling the combustion of the air-fuel mixture in an internal combustion engine in which a digital computer is employed to control the amount of air-fuel mixture metered into the combustion chamber of the engine, the spark-ignition timing of the air-fuel mixture, the recirculation of exhaust gases into the combustion chamber, and the like, in accordance with changes in the operating conditions of the engine.
In a conventional method and apparatus for controlling the combustion of the air-fuel mixture in an engine of this kind, such as for instance, disclosed in U.S. Pat. No. 3,969,614 by David F. Moyer et al. issued on July 13, 1976, a digital computer is employed to calculate values corresponding to proper settings of the various control devices used to control the energy conversion functions of the engine. The digital computer is programmed to repetitively calculate the various values or settings mathematically from an algebraic function or functions describing desired relationships between various settings of the control devices and the sensed condition of the engine. This means that the calculations of the various values are simultaneously executed on a real-time basis at short angular intervals of rotation of the engine output shaft. As a result, the digital computer is required to have a large calculation capacity so as to complete the calculations of the various values at a high speed. Thus, such a conventional engine control apparatus and its digital computer are inevitably complicated in their construction and high in production cost.